Mechanical and microstructural characterization of aluminium powder deposit made by friction stir based additive manufacturing

The full potential application of the powder-based additive friction stir (AFS) process can be hindered due to the consolidation of the powder inside the tool. In this work, a very simple method was proposed to negate this issue. The process was named as additive friction stir processing (AFSP) since its working principle was similar to the friction stir processing (FSP). A layer-by-layer 7 mm thick 3D structure from pure aluminium powder on an aluminium substrate was successfully fabricated by AFSP. The quality of the additive layers was assessed by examining its mechanical properties and microstructural characteristics. An increment of 36, 3, and 54 % in the average ultimate tensile strength, yield strength, and percentage elongation, respectively, were observed when comparing with AA1060-H12. Grain refinement of the filler aluminium powder was noticed. Fine grains with almost equal dimensions in short-transverse and transverse directions were also found, which revealed induced super-plasticity and isotropy in the deposit. The fractographic analysis was in good agreement with the ductile nature of the deposit.